1. Field of the Invention
The present invention relates to an electric power control apparatus and an electric power control system for controlling the amount of power consumed by a plurality of information processing apparatuses.
2. Description of the Related Art
Known conventional electric power control techniques for saving power include target power control that involves establishing a criterion for targeting a power source with respect to power consumed by an apparatus that is driven, and performing electric power control based on that criterion. For example, an amount of power consumption serving as a fixed target is set as a power consumption criterion for an image forming apparatus. Based on this criterion, the image forming apparatus saves power by entering a power saving mode such as a sleep mode in which little power is consumed.
Also, Japanese Patent Laid-Open No. 2003-32397 proposes an invention for efficiently controlling overall power consumption in a system in which a plurality of image forming apparatuses are connected by a network. This invention involves controlling the state of each image forming apparatus in power saving mode, such that waiting time for an image forming apparatus that a user wants to use is minimized. Specifically, it is judged whether the total power of all other image forming apparatuses apart from an image forming apparatus that is judged to have the highest priority level exceeds a target value. If the target value has been exceeded, the other image forming apparatuses are set to a power economizing state. In other words, user-friendliness is improved by setting the image forming apparatus judged to have the highest priority level exceptionally to always be in an operational state.
In other words, while the image forming apparatus that is preferentially always in an operational state can be used at any time, the total amount of power consumption in the overall system is managed with an upper limit value. Consequently, all other image forming apparatuses enter a power economizing state when the amount of power consumption reaches the upper limit, giving rise to a feeling of unfairness among users of low priority image forming apparatuses because they can no longer use those apparatuses. Variability exists among image forming apparatuses belonging to an actual office network environment in terms of function, performance, operating time, and operating content. In order to control the amount of power consumed by image forming apparatuses placed in a variable usage environment, target power control thus needs to be performed with consideration for the factors causing that variability.